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[78.88.45.245]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-64b9ef904bcsm43228684a12.22.2026.01.02.05.57.57 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 02 Jan 2026 05:58:01 -0800 (PST) Message-ID: Date: Fri, 2 Jan 2026 14:57:56 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/7] clk: qcom: gcc: Do not turn off PCIe GDSCs during gdsc_disable() To: Krishna Chaitanya Chundru , Bjorn Andersson , Michael Turquette , Stephen Boyd , Taniya Das , Konrad Dybcio , Bartosz Golaszewski , Shazad Hussain , Sibi Sankar , Bryan O'Donoghue , Melody Olvera , Dmitry Baryshkov , Taniya Das , Dmitry Baryshkov , Imran Shaik , Abel Vesa Cc: linux-arm-msm@vger.kernel.org, linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org, Rajendra Nayak , manivannan.sadhasivam@oss.qualcomm.com, stable@vger.kernel.org References: <20260102-pci_gdsc_fix-v1-0-b17ed3d175bc@oss.qualcomm.com> <500313f1-51fd-450e-877e-e4626b7652bc@oss.qualcomm.com> <4d61e8b3-0d40-4b78-9f40-a68b05284a3d@oss.qualcomm.com> Content-Language: en-US From: Konrad Dybcio In-Reply-To: <4d61e8b3-0d40-4b78-9f40-a68b05284a3d@oss.qualcomm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Proofpoint-GUID: 9gRSI-iW7-8KQUOLZ_UsORYna8Qp2tFQ X-Proofpoint-ORIG-GUID: 9gRSI-iW7-8KQUOLZ_UsORYna8Qp2tFQ X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMTAyMDEyMiBTYWx0ZWRfX8lOL7DTif6iR y+/A2uTX4+CXT0uF/VVlBtK/W0FN75cA9YArdg+O4T4B1OJ4H7/ioFA40CgnyB5krZdS5b88MzZ GKWZmG5GknkJECimSBFfSUMo7YUHU4F/Fhp1NqYc8xufmUkMDhZSFPVK/eoqjTIgaYMfv+WWhav fEVpaVuc/DJ1V5VaNC+EQMu3150SfWV9NAFcRxqA4BQwqI3lwi8E16OotKhwmTjo7lirEIFoNGd WYvbTm9b4mxojKX1WysFiDJx2uub72+iSGW+xRPP8CPclpZXNm3vvG87YwLusoEkwA0gLzhfaD9 04/Y7+UwEl7/BuSp49KU7Sxy9uZxG8WsRr4P79U7GyBWez8200vav5waXSPW0kkMmeWzaOpF7sV XiC98oRqAJOKzh2gvT2on1ad92gnBwpVY81nYas0lkt+RFEgomW8tJTge/ke/4idOqMhYJlI5OG M5ePSyc9B4tS74ErZJw== X-Authority-Analysis: v=2.4 cv=ev7SD4pX c=1 sm=1 tr=0 ts=6957ceea cx=c_pps a=WeENfcodrlLV9YRTxbY/uA==:117 a=FpWmc02/iXfjRdCD7H54yg==:17 a=IkcTkHD0fZMA:10 a=vUbySO9Y5rIA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=LvUvCMLUZ1wwccowk60A:9 a=QEXdDO2ut3YA:10 a=kacYvNCVWA4VmyqE58fU:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2026-01-02_02,2025-12-31_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 bulkscore=0 malwarescore=0 clxscore=1015 adultscore=0 phishscore=0 impostorscore=0 lowpriorityscore=0 spamscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2512120000 definitions=main-2601020122 On 1/2/26 2:19 PM, Krishna Chaitanya Chundru wrote: > > > On 1/2/2026 5:09 PM, Konrad Dybcio wrote: >> On 1/2/26 12:36 PM, Krishna Chaitanya Chundru wrote: >>> >>> On 1/2/2026 5:04 PM, Konrad Dybcio wrote: >>>> On 1/2/26 10:43 AM, Krishna Chaitanya Chundru wrote: >>>>> With PWRSTS_OFF_ON, PCIe GDSCs are turned off during gdsc_disable(). This >>>>> can happen during scenarios such as system suspend and breaks the resume >>>>> of PCIe controllers from suspend. >>>> Isn't turning the GDSCs off what we want though? At least during system >>>> suspend? >>> If we are keeping link in D3cold it makes sense, but currently we are not keeping in D3cold >>> so we don't expect them to get off. >> Since we seem to be tackling that in parallel, it seems to make sense >> that adding a mechanism to let the PCIe driver select "on" vs "ret" vs >> "off" could be useful for us > At least I am not aware of such API where we can tell genpd not to turn off gdsc > at runtime if we are keeping the device in D3cold state. > But anyway the PCIe gdsc supports Retention, in that case adding this flag here makes > more sense as it represents HW. > sm8450,sm8650 also had similar problem which are fixed by mani[1]. Perhaps I should ask for a clarification - is retention superior to powering the GDSC off? Does it have any power costs? >> FWIW I recall I could turn off the GDSCs on at least makena with the old >> suspend patches and the controllers would come back to life afterwards > In the suspend patches, we are keeping link in D3cold, so turning off gdsc will not have any effect. What do you mean by it won't have any effect? > But if some reason we skipped D3cold like in S2idle case then gdsc should not be off, in that case > in resume PCIe link will be broken. Right, obviously Konrad